Edema and Nociception Induced by Philodryas patagoniensis Venom in Mice: A Pharmacological Evaluation with Implications for the Accident Treatment

Antivenom Administration After Rattlesnake Envenoming in Arizona Does Not Directly Diminish Pain

The onset, progression, and severity of pain following rattlesnake envenomation are highly variable between patients. Pain can be severe and persistent, seemingly refractory to opioid analgesics. The ability of antivenom to directly relieve pain has not been well studied. We reviewed poison center charts of rattlesnake envenomations between 1 January 2018, and 31 December 2022. Demographic data as well as details of antivenom usage and pain severity were collected. Patients were coded in one of three categories: without pain (Pain 0), well controlled pain (Pain 1), and opioid refractory pain (Pain 2). A total of 289 patients met the inclusion criteria, with 140 receiving Anavip antivenom and 149 receiving Crofab. Patient characteristics were different between both cohorts. There were no significant differences in the number of Anavip vials used between the Pain 1 and Pain 2 groups. However, patients in the Crofab Pain 2 group received more antivenom compared to Pain 1. Importantly, Pain 3 patients were treated with the highest amount of antivenom in both the Crofab and Anavip cohorts. Despite the higher doses of antivenom used, these patients also experienced the greatest pain. These data suggest that antivenom alone may have minimal analgesic benefits.

Cytotoxicity and inflammation induced by Philodryas patagoniensis venom

The Green racer Philodryas patagoniensis is a snake species from South America and accidents with this genus are often neglected. Therefore, this study aimed to evaluate the toxicological, cytotoxic, and inflammatory potential of P. patagoniensis venom (PpV). The experimental model Artemia salina was used to determine toxicity through the median lethal dose (LD₅₀). Cell viability and genotoxicity were evaluated in human mononuclear cells using the Trypan blue test and the Comet assay, respectively. To assess inflammation, mice had the ventral surface of the right hind paw injected with saline, formalin, and three different concentrations of venom (1, 1.5, and 2 μg. 50 μL^-1). LD₅₀ in A. salina was 461 μg. mL^-1. PpV caused a significant increase in cell death and genotoxicity in human mononuclear cells at two concentrations (575 and 1150 μg. mL^-1). PpV shown also to be a strong agent causing nociception in mice. Paw edema totaled four days at 1.5 μg. 50 μL^-1. The hyperalgesia caused by the venom had a long duration in mice, lasting eight days at all concentrations evaluated. Thus, we evaluated for the first time the toxicological potential of PpV in A. salina model and in leukocytes. We concluded that systemic oxidative stress, which we infer to be in the genesis of cytotoxicity and genotoxicity observed in vitro, and the inflammatory process are part of the pathways that trigger the venom damage cascades. Relevant data for both scientific research and clinical medicine. Nonetheless, studies are needed to elucidate these mechanisms.

Review of the Mechanisms of Snake Venom Induced Pain: It's All about Location, Location, Location

Pain—acute, chronic and debilitating—is the most feared neurotoxicity resulting from a survivable venomous snake bite. The purpose of this review is to present in a novel paradigm what we know about the molecular mechanisms responsible for pain after envenomation. Progressing from known pain modulating peptides and enzymes, to tissue level interactions with venom resulting in pain, to organ system level pain syndromes, to geographical level distribution of pain syndromes, the present work demonstrates that understanding the mechanisms responsible for pain is dependent on “location, location, location”. It is our hope that this work can serve to inspire the molecular and epidemiologic investigations needed to better understand the neurotoxic mechanisms responsible for these snake venom mediated diverse pain syndromes and ultimately lead to agent specific treatments beyond anti-venom alone.

Philodryas (Serpentes: Dipsadidae) Envenomation, a Neglected Issue in Chile

Snakebite envenomation is considered a neglected tropical disease, although it also occurs outside the tropics. In this work, we analyzed the literature on Philodryas species in Chile (Philodryaschamissonis, P.simonsii, and P.tachymenoides) from 1834 to 2019, searching for epidemiological, clinical, and molecular aspects of envenomation. Ninety-one percent of the studies found regarded taxonomy, ecology, and natural history, suggesting that snakebites and venom toxins are a neglected issue in Chile. All snakebite cases reported and toxicological studies concerned the species Philodryaschamissonis. Using 185 distributional records from the literature and museum collections for this species, we show for the first time that the reported snakebite cases correlate with human population density, occurring in the Valparaiso and Metropolitan regions in Central Chile. The reduced number of snakebite cases, which were previously considered as having a low incidence in Chile, may be a consequence of under-reported cases, probably due to the inadequate publication or scarce research on this issue. Absence of information about official pharmacological treatment, post-envenoming sequels, clinical management of particular patient groups (e.g., with non-communicable diseases, pregnant women, and the elderly) was also detected. In conclusion, despite having over 185 years of literature on Chilean snakes, knowledge on the envenomation of Philodryas genus remains scarce, seriously affecting adequate medical handling during an ophidic accident. This review highlights the need to develop deep research in this area and urgent improvements to the management of this disease in Chile.